1. Field of the Invention
The invention relates to a catalytic material for reducing nitrous oxides in flue gases in the presence of ammonia.
2. Description of the Prior Art
It is known to reduce nitrous oxides in the flue gases catalytically to molecular nitrogen in the presence of ammonia (DE-AS No. 24 58 888=U.S. Pat. No. 4,085,198). To this end, the gas mixture is brought into contact with a catalyst in the temperature range of 150.degree. to 550.degree. C.; this catalyst consists of an intimate mixture of the following components:
(A) titanium in the form of oxides, PA1 (B) at least one metal from the group PA1 (C) tin in the form of oxides, PA1 (D) metals from the group beryllium, magnesium, zinc, boron, aluminum, yttrium, rare earth elements, silicon, niobium, antimony, bismuth and manganese in the form of oxides,
B-1 iron and vanadium in the form of oxides and/or sulfates and/or the group PA2 B-2 molybdenum, tungsten, nickel, cobalt, copper, chromium and uranium in the form of oxides,
where the components are present in the atom ratios A to B to C to D=(1) to (0.01-10) to (0-0.2) to (0-0.15).
Useful results can be achieved with such a catalytic material in the reduction of the nitrous oxides. The conversion of NO into N.sub.2 at the maximum conversion rate is limited here to a relatively small temperature range.